Crystalline polyolefin resin composition and electrical insulating part comprising said composition

ABSTRACT

The invention relates to crystalline polyolefin resin compositions obtained by blending 40 to 85% by weight of a crystalline propylene polymer, 3 to 40% by weight of an inorganic filler, 7 to 30% by weight of a halogen-containing flame retardant comprising ethylenebistetrabromophthalimide, decabromodiphenylethane, or their mixture, and 3 to 15% by weight of a flame retarding auxiliary; and electrical insulating parts obtained by molding the crystalline polyolefin resin composition. 
     By using the crystalline polyolefin resin compositions of the invention, blooming (separation, in a powder-like form, of an ingredient) on the surface of a mold at the time of injection molding can be prevented, deterioration in appearance of final products due to the transfer of the bleeded ingredient to the surface of the mold is obviated, and decrease in productivity caused by wiping the bleeded ingredient off the mold can be avoided. In addition to the bleeding property onto the mold, mechanical properties (tensile strength and bending elastic modulus), electrical property, bleeding property of final products, appearance of final products, and flame retardancy can be satisfied at the same time by using the composition. Therefore, the crystalline polyolefin resin compositions of the present invention can widely be used for electrical insulating parts including deflection yoke separators.

TECHNICAL FIELD

The present invention relates to crystalline polyolefin resincompositions. More specifically, the present invention relates tocrystalline polyolefin resin compositions obtained by blending aninorganic filler, halogen-containing flame retardant, and flameretarding auxiliary to a crystalline propylene polymer resin, andpreferably used for electrical insulating parts such as a separator fordeflection yokes.

BACKGROUND ART

Heretofore, deflection yoke separators are used for domestic televisionsand a display of computers. As the material for the separators, (1)modified polyphenylene oxides (hereinafter referred to as modified PPO),(2) polybutylene terephthalate resins blended with a flame retardant andglass fibers (hereinafter referred to as PBT blended with flameretardant and glass fiber), and (3) polypropylene resins blended with atalc and flame retardant are used.

Modified PPO has a defect that the cost of final products is high basedboth on the cost of material and the productivity at molding, whereas itis widely used as the material for deflection yoke separators fordomestic televisions and a display of computers.

PBT blended with a flame retardant and glass fibers has a defect that itis inferior in tracking resistance. If the tracking resistance is poor,when televisions are used in an environment of a high temperature and ahigh humidity, outside surface of the deflection yoke separatorshumidified and covered with dust is partially carbonized by a minuteelectric discharge to electrically continue thereby producing aninferior insulation. This deterioration in the tracking resistance iscaused by the molecular structure of resins used as the material. Forinstance, since the bond between carbon atoms in benzene ring is strong,such resins as PBT having benzene ring within the molecule are hardlygasified by the heat energy of the minute electrical discharge, and freecarbon atoms in the graphite structure remain on the surface tofacilitate the electrical continuing thereby decreasing the trackingresistance. On the other hand, polypropylene resins are considerablyexcellent in the tracking resistance since they do not have benzene ringin the molecule. Accordingly, polypropylene resins are most suitable asthe material for deflection yoke separators from the viewpoint of thetracking resistance.

Polypropylene resins blended with a talc and flame retardant arematerials which improved the tracking resistance of the PBT blended witha flame retardant and glass fiber mentioned above. In the materials, ahalogen-containing flame retardant, decabromodiphenyl ether,dodecachlorododeca-hydrodimethanodibenzodichlorooctene, or their mixtureis used as flame retardant.

However, they have a problem that a mechanical property (tensilestrength) decreases due to the use of the halogen-containing flameretardant. Further, when they are used at a high temperature, flameretardancy decreases and appearance of final products deteriorates sincethe flame retardant is bloomed (phenomenon of separation, in apowder-like form, on the surface of final products). Specifically, whendeflection yoke separators are injection molded by using a polypropyleneresin composition blended with a talc and a flame retardant, thehalogen-containing flame retardant mentioned above is bloomed onto amold (phenomenon of separation, in a powder-like form, on the surface ofa mold), the bleeded ingredient adhered on the surface of the mold istransferred on the surface of molded articles, and thus the appearanceof deflection yoke separators deteriorates. Besides, the productivityextremely decreases since the production is discontinued and a work forwiping off the bleeded flame retardant is conducted to obtain finalproducts having a good appearance,.

Whereas ethylene-vinyl acetate copolymers (EVA), aliphatic carboxylicacids, or salts of aliphatic carboxylic acids are generally used asadditive for suppressing the bleeding phenomenon mentioned above, thereexists a problem that a mechanical property (rigidity) decreases and thecost of the material increases.

An object of the present invention is to solve the problems in the priorart mentioned above, and to provide crystalline polyolefin resincompositions which are balanced in cost, and every characteristics ofmoldability, mechanical properties (tensile strength and rigidity),impact resistance, electrical properties, and flame retardancy, andwhich avoid the production of inferior appearance of molded productssuch as deflection yoke separators due to the bleeding of the flameretardant onto the mold when propylene resins blended with a talc andflame retardant are molded, and avoid the decrease in the productivity;and to provide electrical insulating parts comprising the composition.

DISCLOSURE OF THE INVENTION

As a result of the investigations by the present inventors forpreventing the bleeding of a flame retardant onto a mold at the time ofinjection molding, it has been found that the bleeding of a flameretardant onto the mold is remarkably improved by usingethylenebistetrabromophthalimide and/or decabromodiphenylethane ashalogen-containing flame retardant, leading to the accomplishment of thepresent invention.

That is, the invention claimed by the present application is as follows:

(1) A crystalline polyolefin resin composition comprising 40 to 85% byweight of a crystalline propylene polymer, 3 to 40% by weight of aninorganic filler, 7 to 30% by weight of decabromophenylethane as flameretardant, and 3 to 15% by weight of a flame retarding auxiliary.

(2) The crystalline polyolefin resin composition recited in (1) abovewherein the crystalline propylene polymer is a propylene homopolymer ora propylene-ethylene copolymer.

(3) The crystalline polyolefin resin composition recited in (2) abovewherein the propylene homopolymer has a melt flow rate of 1.0 to 80 g/10min.

(4) The crystalline polyolefin resin composition recited in (2) abovewherein the propylene-ethylene copolymer has a content of ethylene of 2to 35% by weight and a melt flow rate of 1.0 to 40 g/10 min.

(5) The crystalline polyolefin resin composition recited in any one of(1) to (4) above wherein the inorganic filler is a talc, mica, silica,calcium carbonate, barium sulfate, or glass fiber.

(6) The crystalline polyolefin resin composition recited in any one of(1) to (5) above wherein the flame retarding auxiliary is an antimonycompound or boron compound.

(7) An electrical insulating part obtained by molding the crystallinepolyolefin resin composition defined in any one of (1) to (6) above.

(8) A crystalline polyolefin resin composition comprising 40 to 85% byweight of a crystalline propylene polymer, 3 to 40% by weight of aninorganic filler, 7 to 30% by weight of a mixture ofdecabromophenylethane with ethylenebistetrabromophthalimide, as flameretardant, and 3 to 15% by weight of a flame retarding auxiliary.

As the crystalline propylene polymer used in the present invention,crystalline propylene homopolymers having a melt flow rate (MFR: amountof melted resin extruded for 10 min when 2.16 kg of a load is applied at230° C.) of 1.0 to 80 g/10 min, and crystalline propylene-ethylenecopolymers having an ethylene content of 2 to 35% by weight and a meltflow rate of 1.0 to 40 g/10 min are preferable. Particularly whenpropylene-ethylene copolymers are used, crystalline propylene-ethyleneblock copolymers are preferable. Amount of the crystalline propylenepolymers to be blended is 40 to 85% by weight and preferably 50 to 60%by weight from the viewpoint of mechanical properties.

Copolymers such as modified polyolefin resins, polyethylenes,propylene-ethylene copolymers, and polybutenes may be used whennecessary. The modified polyolefin resins are obtained by melting andkneading these polyolefin resins with an unsaturated carboxylic acid orits anhydride (for example, maleic anhydride) in the presence of anorganic peroxide. For example, modified polyethylenes, modifiedpropylene homopolymers, modified propylene-ethylene copolymers, andmodified polybutenes are mentioned as the modified polyolefin resin, andparticularly modified propylene-ethylene copolymers are preferable.Amount of these resins to be blended is preferably in the range of 3 to8% by weight based on the amount of the crystalline propylene polymer.

Inorganic fillers used in the present invention are not particularlyrestricted in the aspect of particle size. While it is usuallysufficient to use inorganic fillers which are commercially available asones for thermoplastic resins, the fillers having a large aspect ratioare preferable. More specifically, talcs, micas, silicas, calciumcarbonate, barium sulfate, and glass fibers are mentioned. Whileinorganic fillers may be used as they remain untreated, the fillerssurface of which particles is covered with one of various kind oforganic titanate type coupling agents, silane type coupling agents,fatty acids, metal salts of fatty acids, esters of fatty acids for thepurpose of increasing adhering property to or dispersing property in amatrix resin may also be used. Amount of the inorganic fillers to beblended is 3 to 40% by weight and preferably 5 to 25% by weight. Whenthe amount is less than 3% by weight, the effect on improvement inmechanical properties (tensile strength and rigidity) of molded productsto be obtained is small, but when it exceeds 40% by weight, impactstrength of molded products decreases.

Halogen-containing flame retardant used in the present invention isdecabromodiphenylethane or its mixture withethylenebistetrabromophthalimide. These halogen-containing flameretardant have a melting point higher than 200° C., and are excellent inbleeding characteristic of the product and mold at the time of molding.Particularly, decabromodiphenylethane is preferable from the viewpointof impact resistance. Amount of the halogen-containing flame retardantto be blended is 7 to 30% by weight and preferably 10 to 25% by weight.When the amount of blending is less than 7% by weight, flame retardancyto be expected of molded articles can not be attained by using theresulting resin compositions. When the amount exceeds 30% by weight,mechanical property (tensile strength) and impact resistance of moldedarticles from the resin compositions and granulating ability at the timeof pelletizing the resin compositions deteriorate.

As the flame retarding auxiliary used in the present invention, antimonycompounds such as antimony trioxide and boron compounds such as zincborate and borax are mentioned. Amount of the flame retarding auxiliaryto be blended is 3 to 15% by weight from the viewpoint of flameretardancy, and preferably 1/4 to 1/2 of the weight of thehalogen-containing flame retardant to be used.

In addition to the components mentioned above, a coloring agent such asa dye and pigment, nucleator, lubricating agent, antioxidant, heatstabilizer, light stabilizer, release agent, cross-linking auxiliary,radical generator, and foaming agent can be added to the resincompositions of the present invention, when necessary.

While method for producing the resin compositions of the presentinvention is not particularly restricted, it can be performed, forinstance, by introducing the crystalline propylene polymer resinmentioned above, and a specific amount of an inorganic filler,halogen-containing flame retardant, and flame retarding auxiliary in astirring and mixing apparatus such as a Henschel mixer or super-mixer,stirring them for 30 sec to 3 min to mix, melting and kneading theresulting mixture by using a Banbury type mixer, roll, or extruder, andthen pelletizing. As the melting and kneading temperature, 180° to 280°C. is preferable and 200° to 250° C. is more desirable.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention is specifically described with reference toExamples and Comparative Examples. However, it should be understood thatthe present invention by no means restricted by such examples. Variouskind of tests in Examples and Comparative Examples were carried out bythe following methods:

1) Mechanical Property

Mechanical properties (tensile strength and rigidity) were evaluated bydetermining tensile strength (according to JIS K-7113) and bendingelastic modulus (according to JIS K-7203).

2) Impact Resistance

Impact resistance was evaluated by determining Izod impact strength(according to JIS K-77110).

3) Electrical Property

Electrical property was evaluated by determining arc resistance(according to ASTM D-495).

4) Bleeding Property of Final Product

After a sample peace of 50×50×2 mm prepared by an injection molding wasleft in an oven at 100° C. for 240 hrs, its appearance was observed withthe naked eye. Bleeded products were graded as poor and not-bleeded onesas good.

5) Bleeding Property onto Mold

After molding was conducted 100 shots by an injection molding by using amold for a sample piece of 100×50×2 mm, the surface of the mold wasobserved with the naked eye. Bleeded cases were graded as poor andnot-bleeded cases as good.

6) Appearance of Final Product

After a sample piece of 100×50×2 mm was molded 100 shots, the surface ofa sample piece was observed with the naked eye. Sample pieces to which ableeded ingredient was transferred from the mold were graded as poor andones not transferred were graded as good.

7) Flame Retardancy

Flame retardancy was evaluated by conducting a flame test according tothe vertical flame test defined in America UL Standard, Subject 94 (UL94) by using a sample piece of 127×12.7×1.6 mm prepared by an injectionmolding.

EXAMPLES 1 THROUGH 12, AND COMPARATIVE EXAMPLES 1 THROUGH 24

As Examples 1 through 12 and Comparative Examples 1 through 12, acrystalline propylene homopolymer resin having a melt flow rate of 5g/10 min (hereinafter, sometimes referred to as PP homopolymer) or acrystalline propylene-ethylene block copolymer resin having a melt flowrate of 5 g/10 min and having an ethylene content of 8.5% by weight(hereinafter, sometimes referred to as PP block copolymer), and aprescribed amount of each of a talc as inorganic filler,ethylenebistetrabromophthalimide (Trade name: Saytex BT93; produced byAlbemarle Corp.) or decabromodiphenyl-ethane (Trade name: Saytex 8010;produced by Albemarle Corp.) as flame retardant, and antimony trioxideas flame retarding auxiliary, as described in Tables 1 and 2 shownbelow, were charged in a Henschel mixer (produced by Mitsui Miike KaKoCo., Ltd.), and stirred for 1 min to mix.

The mixture thus obtained was melted and kneaded at a melt-kneadingtemperature of 230° C., and extruded by using a twin extruder having adie orifice diameter of 30 mm, and pelletized.

Also, as Comparative Examples 13 through 24, a prescribed amount of eachof the blending components were stirred to mix in a Henschel mixer andtumbler according to Examples 1 through 12 with the exception thatdecabromodiphenyl ether (Trade name: Saytex 102R; produced by AlbemarleCorp.) was used as halogen-containing flame retardant, as described inTable 3 shown below, and melted, kneaded, and extruded by using a twinextruder having a die orifice diameter of 30 mm, and pelletized.

Next, sample pieces of a prescribed shape were molded by an injectionmolding by using pellets obtained in each of Examples and ComparativeExamples at a resin temperature of 250° C. and a mold temperature of 50°C., and subjected to evaluation of mechanical properties (tensilestrength and bending elastic modulus), electrical property (arcresistance), bleeding property of final product, bleeding property ontomold, appearance of final product, and flame retardancy. The results areshown together in Tables 1 to 3.

As will be clear from Tables 1 to 3, molded products obtained inExamples 1 through 12 in which a resin composition of the presentinvention was used were extremely well balanced between characteristicssuch as mechanical properties (tensile strength and bending elasticmodulus), impact resistance, electrical property (arc resistance),bleeding property of final product, bleeding property onto mold,appearance of final product, and flame retardancy. Particularly,inferiority in the bleeding property onto mold and appearance of finalproduct which are a defect of decabromodiphenyl ether, as flameretardant, was capable of being solved by usingdecabromo-diphenylethane.

That is, as will be clear from the comparison of Examples 1 to 6 withComparative Examples 1 to 6 and Comparative Examples 13 to 18, in thecase where a base polymer is a crystalline propylene homopolymer, whendecabromodiphenyl ether was used as halogen-containing flame retardant,bleeding of final product occurred. However, that problem was found tosolve by using ethylenebistetrabromo-phthalimide ordecabromodiphenylethane.

Further, as will be clear from the comparison of Comparative Examples 1through 12 wherein ethylenebistetrabromophthalimide was used withExamples 1 through 12 wherein decabromodiphenylethane was used,respectively, as halogen-containing flame retardant; in the aspect offlame retardant, the cases where decabromo-diphenylethane was used weresuperior in impact resistance.

                                      TABLE 1    __________________________________________________________________________    Comparative Example 1   2    3    4    5    6    __________________________________________________________________________    Blend (% by weight)    PP homopolymer      80  75   70   63   53   65    PP block copolymer  0   0    0    0    0    0    Talc                5   10   15   15   15   20    Ethylenebistetrabromophthalimide                        10  10   10   15   25   10    Antimony trioxide   5   5    5    7    7    5    Tensile strength (kgf/cm.sup.2)                        360 350  350  320  330  320    Bending elastic modulus (kgf/cm.sup.2)                        24,000                            27,000                                 30,000                                      33,000                                           35,000                                                34,000    Izod impact strength (kgf · cm/cm.sup.2)                        4.2 4.0  3.7  3.5  3.0  3.3    Arc resistance (sec)                        110 105  100  75   70   75    Bleeding property of final product (100° C.,                        Good                            Good Good Good Good Good    240 hr)    Bleeding property onto mold (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Appearance of final product (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Flammability (UL94 vertical method, 1.6 mm,                        V-2 V-2  V-2  V-1  V-0  V-2    class)    __________________________________________________________________________    Comparative Example 7   8    9    10   11   12    __________________________________________________________________________    Blend (% by weight)    PP homopolymer      0   0    0    0    0    0    PP block copolymer  80  75   70   63   53   65    Talc                5   10   15   15   15   20    Ethylenebistetrabromophthalimide                        10  10   10   15   25   10    Antimony trioxide   5   5    5    7    7    5    Tensile strength (kgf/cm.sup.2)                        280 270  260  250  240  250    Bending elastic modulus (kgf/cm.sup.2)                        20,000                            24,000                                 27,000                                      30,000                                           31,000                                                30,000    Izod impact strength (kgf · cm/cm.sup.2)                        4.9 4.5  4.1  4.0  3.5  4.0    Arc resistance (sec)                        110 110  100  75   70   75    Bleeding property of final product (100° C.,                        Good                            Good Good Good Good Good    240 hr)    Bleeding property onto mold (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Appearance of final product (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Flammability (UL94 vertical method, 1.6 mm,                        V-2 V-2  V-2  V-1  V-0  V-2    class)    __________________________________________________________________________

                                      TABLE 2    __________________________________________________________________________    Example             1   2    3    4    5    6    __________________________________________________________________________    Blend (% by weight)    PP homopolymer      80  75   70   63   53   65    PP block copolymer  0   0    0    0    0    0    Talc                5   10   15   15   15   20    Decabromodiphenylethane                        10  10   10   15   25   10    Antimony trioxide   5   5    5    7    7    5    Tensile strength (kgf/cm.sup.2)                        360 350  350  320  310  310    Bending elastic modulus (kgf/cm.sup.2)                        24,000                            27,000                                 29,000                                      31,000                                           33,000                                                31,000    Izod impact strength (kgf · cm/cm.sup.2)                        5.0 4.5  4.2  3.8  3.5  3.8    Arc resistance (sec)                        110 105  100  80   70   75    Bleeding property of final product (100° C.,                        Good                            Good Good Good Good Good    240 hr)    Bleeding property onto mold (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Appearance of final product (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Flammability (UL94 vertical method, 1.6 mm,                        V-2 V-2  V-2  V-1  V-0  V-2    class)    __________________________________________________________________________    Example             7   8    9    10   11   12    __________________________________________________________________________    Blend (% by weight)    PP homopolymer      0   0    0    0    0    0    PP block copolymer  80  75   70   63   53   65    Talc                5   10   15   15   15   20    Decabromodiphenylethane                        10  10   10   15   25   10    Antimony trioxide   5   5    5    7    7    5    Tensile strength (kgf/cm.sup.2)                        270 260  250  240  230  240    Bending elastic modulus (kgf/cm.sup.2)                        20,000                            24,000                                 27,000                                      30,000                                           31,000                                                30,000    Izod impact strength (kgf · cm/cm.sup.2)                        5.5 4.9  4.5  4.4  4.0  4.5    Arc resistance (sec)                        115 105  100  80   70   75    Bleeding property of final product (100° C.,                        Good                            Good Good Good Good Good    240 hr)    Bleeding property onto mold (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Appearance of final product (after 100                        Good                            Good Good Good Good Good    shots of injection molding)    Flammability (UL94 vertical method, 1.6 mm,                        V-2 V-2  V-2  V-1  V-0  V-2    class)    __________________________________________________________________________

                                      TABLE 3    __________________________________________________________________________    Comparative Example 13  14   15   16   17   18    __________________________________________________________________________    Blend (% by weight)    PP homopolymer      80  75   70   63   53   65    PP block copolymer  0   0    0    0    0    0    Talc                5   10   15   15   15   20    Decabromodiphenylether                        10  10   10   15   25   10    Antimony trioxide   5   5    5    7    7    5    Tensile strength (kgf/cm.sup.2)                        360 350  350  320  330  320    Bending elastic modulus (kgf/cm.sup.2)                        24,000                            27,000                                 30,000                                      33,000                                           35,000                                                33,000    Izod impact strength (kgf · cm/cm.sup.2)                        4.5 4.0  3.8  3.5  3.0  3.3    Arc resistance (sec)                        110 105  100  80   70   75    Bleeding property of final product (100° C.,                        Poor                            Poor Poor Poor Poor Good    240 hr)    Bleeding property onto mold (after 100                        Poor                            Poor Poor Poor Poor Poor    shots of injection molding)    Appearance of final product (after 100                        Poor                            Poor Poor Poor Poor Poor    shots of injection molding)    Flammability (UL94 vertical method, 1.6 mm,                        V-2 V-2  V-2  V-1  V-0  V-2    class)    __________________________________________________________________________    Comparative Example 19  20   21   22   23   24    __________________________________________________________________________    Blend (% by weight)    PP homopolymer      0   0    0    0    0    0    PP block copolymer  80  75   70   63   53   65    Talc                5   10   15   15   15   20    Decabromodiphenylether                        10  10   10   15   25   10    Antimony trioxide   5   5    5    7    7    5    Tensile strength (kgf/cm.sup.2)                        280 270  260  250  240  250    Bending elastic modulus (kgf/cm.sup.2)                        20,000                            24,000                                 27,000                                      30,000                                           31,000                                                30,000    Izod impact strength (kgf · cm/cm.sup.2)                        4.9 4.5  4.1  4.0  3.5  4.0    Arc resistance (sec)                        105 105  100  75   70   75    Bleeding property of final product (100° C.,                        Good                            Good Good Good Good Good    240 hr)    Bleeding property onto mold (after 100                        Poor                            Poor Poor Poor Poor Poor    shots of injection molding)    Appearance of final product (after 100                        Poor                            Poor Poor Poor Poor Poor    shots of injection molding)    Flammability (UL94 vertical method, 1.6 mm,                        V-2 V-2  V-2  V-1  V-0  V-2    class)    __________________________________________________________________________

INDUSTRIAL APPLICABILITY

Since the crystalline polyolefin resin compositions of the presentinvention comprise a crystalline propylene polymer, inorganic filler,specific halogen-containing flame retardant, and flame retardingauxiliary each blended therein, blooming (separation in a powder-likeform) onto the surface of mold at the time of injection molding can beprevented, inferiority in appearance of final products due totransferring of bleeded ingredient onto the mold is removed, anddecrease in productivity due to wiping up of bleeded ingredient can beavoided.

Further, since the crystalline polyolefin resin compositions of thepresent invention can be satisfied not only with bleeding property ontothe mold, but also with mechanical properties (tensile strength andbending elastic modulus), impact resistance, electrical property,bleeding property of final product, appearance of final product, andflame retardancy at the same time, the compositions can widely be usedfor electrical insulating parts such as plug covers, switchboard covers,connector covers, code reel cases, noise filter bobbins, parts ofcopiers, parts of refrigerators, and parts of tuners includingdeflection yoke separators.

We claim:
 1. A crystalline polyolefin resin composition comprising 40 to85% by weight of a crystalline propylene homopolymer having a melt flowrate of 1.0 to 80 g/10 min or a crystalline propylene-ethylene blockcopolymer having an ethylene content of 2 to 35% by weight and a meltflow rate of 1.0 to 40 g/10 min, 3 to 40% by weight of an inorganicfiller, 7 to 30% by weight of decabromodiphenylethane as flameretardant, and 3 to 15% by weight of a flame retarding auxiliary.
 2. Thecrystalline polyolefin resin composition according to claim 1, whereinsaid inorganic filler is a talc, mica, silica, calcium carbonate, bariumsulfate, or glass fiber.
 3. The crystalline polyolefin resin compositionaccording to claim 1 wherein said flame retarding auxiliary is anantimony compound or boron compound.
 4. The crystalline polyolefin resincomposition according to claim 2 wherein said flame retarding auxiliaryis an antimony compound or boron compound.
 5. An electrical insulatingpart obtained by molding said crystalline polyolefin resin compositiondefined in any one of claims 1 to
 3. 6. A crystalline polyolefin resincomposition comprising 40 to 85% by weight of a crystalline propylenehomopolymer having a melt flow rate of 1.0 to 80 g/10 min or acrystalline propylene-ethylene block copolymer having an ethylenecontent of 2 to 35% by weight and a melt flow rate of 1.0 to 40 g/10min, 3 to 40% by weight of an inorganic filler, 7 to 30% by weight of amixture of decabromodiphenylethane and ethylenebistetrabromophthalimideas flame retardant, and 3 to 15% by weight of a flame retardingauxiliary.